DE Shaun Phillips had plenty of reason to celebrate during his first year in Denver. / Christopher Hanewinckel, USA TODAY Sports

by Lindsay H. Jones, USA TODAY Sports

by Lindsay H. Jones, USA TODAY Sports

ENGLEWOOD, Colo. - Shaun Phillips remembers the very first time he chased down and started yapping with Philip Rivers.

Neither of them was even in the NFL yet.

Opponents at the 2004 Senior Bowl in Mobile, Ala., Phillips, now a Denver Broncos defensive end, recently recalled his introduction to Rivers, quarterback of the San Diego Chargers, which came on a play as Phillips followed Rivers out of bounds.

"I was like, 'You better run out,' " Phillips said. "And he was like, 'What are you going to do?' "

They didn't know then that they would wind up teammates in San Diego from 2004 through 2012 or, eventually, division rivals after Phillips signed with Denver as a free agent last April.

In Sunday's AFC divisional playoff game, they'll meet as opponents for just the fourth time - that 2004 Senior Bowl and two AFC West games this season. Finally allowed to hit Rivers, Phillips took his ex-mate down for two of his team-best 10 sacks in the regular season.

"What is funny is (Rivers) gets a bad rep - everyone thinks he's talking trash, saying cuss-words and stuff like that. But the guy doesn't even curse," Phillips said. "But he is competitive."

How much Phillips and his Broncos teammates can pressure Rivers on Sunday could be critical to Denver's chances to end San Diego's five-game winning streak while notching the first postseason win of the Peyton Manning era. The Broncos sacked Rivers six times in the regular-season meetings - four in their win at San Diego and two in the Dec. 12 loss in Denver. Rivers and the Chargers converted 50% (6-of-12) of their third-downs in that second meeting.

"They've done an excellent job throughout the year on third down, getting to third-and-manageables. Obviously that's been very big for them," Broncos defensive coordinator Jack Del Rio said.

That's where the Broncos need Phillips, who has only one sack in the last six games.

It wasn't apparent when Phillips quietly came to Denver how much the Broncos would ultimately need him. When he signed, the plan was for Phillips to be a complementary pass rusher to outside linebacker Von Miller while helping alleviate the free agency departure of Elvis Dumervil.

Now it's difficult to picture the Denver defense without him. Miller missed the first six games of 2013 due to a suspension and was lost to a torn anterior cruciate ligament in December. Pressed into starting duty, Phillips had 5.5 of his sacks in games played without Miller.

"I think he pushed the young d-linemen that compete against him. He's a true competitor, and he was a dominant guy for the Chargers for a long time," Broncos linebacker Wesley Woodyard said. "I'm happy he's on our team."

The two earlier matchups against the Chargers have been special for Phillips and two other former Chargers teammates who joined him in Denver this year, starting right guard Louis Vasquez and veteran cornerback Quentin Jammer.

"I love playing football, and I'm going to play my heart out, and Quentin is going to play his heart out," Phillips said. "I think the most important thing is they accepted us with open arms here, and it makes you want to play.